Apparatus for bending tubing



Nov. 2s, 1,901 w. @HILL 3,010,507

APPARATUS FOR BENDING TUBING Filed July '7, 1958 United States Patent O 3,010,507 APPARATUS FOR BENDING TUBING Walter P. Hill, 22183 Telegraph Road, Detroit 19, Mich. Filed July 7, 1958, Ser. No. 747,062 6 Claims. (Cl. 153-32) This invention relates to apparatus for bending tubes and particularly to an apparatus for bending a piece of tubing without using an incompressible ller material within the tubing.

In the past, tubing has been bent to form elbows yand `the like by various methods. One method is to place a sectional mandrel capable of being bent to the desired angle within the tubing and bending the tubing and mandrel together, the mandrel preventing the collapsing of the tubing at the bend. Another method is to use a solid mandrel with a sheep nose insented part way into the tubing, the tubing being bent over the end of the sheep nose of the mandrel.

A third method for bending tubing is to completely ll a piece of tubing with an incompressible filler material, such as a 4mixture of -lead `and bismuth, and to force the tubing with the filler material therein through a passageway in a split die having a curved portion or bend therein corresponding [to the bend desired to be formed in the tubing. The incompressible ller material, of course, prevents fthe tubing from collapsing or deforming as it is pushed around the curved portion of the passageway.

It is one object of the present invention to provide an apparatus for bending tubing that eliminates the need for insert-ing mandrels within the tubing to form the bend therein, but still enables the tubing to be bent sharply with a smaller radius of curvature than obtainable with the above-described prior art methods employing mandrels.

It is another object of the present invention to improve upon the third mentioned method for bending tubing by providing an apparatus for bending the tubing without requiring the use of the incompressible filler material to prevent the tube from collapsing as it is pushed around the curved portion of the passageway in the split die.

It is a further object of the invention to provide an apparatus for bending tubing in a rapid, economical manner without heavyin-g up or wrinking the tubing at the bent portion thereof.

Other objects, features and advantages of the present invention will become apparent from the following detailed description 'taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side view of an apparatus for bending tubing embodying features of the present invention with portions thereof omitted to more clearly illustrate the apparatus;

FiG. 2 is a sectional view taken along the line 2 2 of FIG. l; Y

FIG. 3 -is a sectional view taken along the line 3 3 of FIG. 1;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 1;

FIG. 5 is a view similar to FIG. 1 illustrating a mod-iication of the apparatus of FIG. l; and

FIG. 6 is a sectional view taken along the line 66 of FIG. 5.

Referring to the drawings, an apparatus embodying ice features of the present invention is comprised of a split die 10 having two die portions 12 and 14. Each die portion has a semi-cylindrical groove 16 and 18 formed therein, which cooperate to form a cylindrical passageway 20 when the die portions are joined together as illustrated in FIG. 2. As most clearly illustrated in FIG. l, it will be observed that the passageway 20 has a curved portion 22 intermediate the ends thereof.

With a split die of this type, a piece of tubing 24 can be pushed through the passageway 20 and around the curved pont-ion 22 to the position illustrated in dotted and dashed lines in FIG. 1 to form the desired bend in the tubing 24. It will be observed that the right or leading end of the tubing 24 is tapered so that the upper portion thereof is in etlect longer than the lower portion thereof to insu-re that the leading end of the tubing will be square after it has been pushed around the curved portion 22.

As explained previously, in bending tubing in this manner, the prior art completely iilled the Itubing 24 with an incompressible filler material, such as a mixture of lead and bismuth, so that the tubing would not col-lapse when pushed around the curved portion 22 of the passageway. Then, of course, after the tubing had been completely bent and removed from the split die 10, the tubing was heated to a sutiicient temperature to melt the mixture of lead and bismuth so as to remove it from 'the tubing.

The apparatus of the present invention eliminates the need for employing the incompressible iiller material and consequently eliminates the extremely undesirable and time consuming step of heating the tubing to remove the ller material While still employing the same type of split die and bending the tubing in substantially thev same m-anner.

This is accomplished by mounting a spl-it roller 26 on the die 10 adjacent the convex side of the curved portion 22 of the passageway. The split rolfler 26 is comprised of two identical rollers 28 and 30 rotatably mounted on the die portions 12 and 14 by shafts 32 `and 34, respectively. As most clearly illustrated in FIG. 2, it will be observed that each of the rollers have a concave arcuate periphery in cross section with a radius of curvature substantial'ly the same as the radius of the passageway 20. With this construction, the peripheries of the rollers 28 and 30 cooperate to form the lower half of the wall of the convex side 0f the curved portion 22 of the passageway 20 and can split apant when the die portions 12 and 14 are split apart to permit the tubing to be removed after it has been bent.

When the split roller 26 is provided, tubing 24 can be pushed through the passageway 20 around the curved portion 22 and over the split roller 26 without heavying up or wrinkling at the bend in the tubing, and without irreparable collapsing. However, the leading end of the tubing 24 may lose its circular shape ater the tubing has been bent and, therefore, a mandrel 38 is provided for reshaping the leading end. The mandrel 38 has a conventional sheep nose 40 which is adapted to be inserted in the leading end of the tubing 24 after it has been bent and assumes the dotted line position illustrated in FIG. l. The mandrel 38 may be reciprocated into and out of the leading end of the ltubing 24 after it has been bent by any suitable means, such as by a hydraulic ram 42, for example, wh-ich normally maintains the mandrel 38 in a retracted position so that it clears the leading end of the tubing 24 `after it has been bent.

In operation, the tubing 24 ispushed through the passageway 20, around the curved portion 22 and over the split roller 26 luntil it assumes the dotted yand dashed line position illustrated in FIG. 1. 'Ihe hydraulic ram 42 is then actuated to push the mandrel 38 upwardly so that the sheep nose 40 thereof enters the leading end of the tubing and urges it against the walls of the passageway so that it assumes its original cylindrical shape. The hydraulic ram 42 is then retracted so that the mandrel 38 clears the leading end of the tubing 24 and the die portions 12 `and =14 are pulled apart to permit the completely bent tubing to be removed.

In some cases, it may be desirable to rotatably drive the split rolier 26 as the tubing 24 Vis pushed around the curved portion 22 of the passageway so that the Ysplit roller in effect pulls or leads the tubing around the curved portion. This practice of rotatably driving the split roller has been found to be particularly desirable for bending tubing of larger diameters.

Of course, any suitable mechanism. may be employed for rotatably driving fthe spiit roller 26, such as that -illustrated in FIGS. 5 and 6, for example, wherein a rack 44 has a tongue 46 thereon slidably disposed within a mating groove 48 in the die portion 12. The rack 44 has teeth 50 on the lower edge .thereof which mesh with Vthe Vteeth of a pinion gear 52 which is keyed to la shaft 54. The roller 2S is keyed to the other end of the shaft 54 so that it is adapted to berotatably driven by the pinion gear 52. The roller 30 is rotatably mounted on the die portion 14 by the shaft 34 as before, and suitable pins 56 or the like may be provided on the face of the rofller 28 so a-s to project within suitable holes in the face of the roller 30 when they are positioned together as illustrated in FIG. 6 so that the roller 30 can be rotatably driven by the roller 28.

With this construction, the die portions 12 and 14 and the rollers 28 and 30 may be split apart, as previously described, and ywhen mated together as illustrated inVFIG. 6, the rollers 28 and 30 can be rotatably driven by the reciproca-tion of the [rack 44. A hydraulic ram 58 or the like, may be provided `for pushing the tubing 24 through the passageway 20, as previously described, and the left end of lthe rack 44, as viewed in FIG. 5, m-ay be connected :to the piston rod of the ram 58, as at 60, so that it is actuated simultaneously with the advancement of the tubing through the passageway to rotatably drive the split roller 26.

The tubing 24 is illustrated in FIG. 5 -in the nal position to which it is pushed by a head 62 on the end of the piston rod of the ram 58 and the mandrel 38 is illustrated as advanced to its uppermost position for correcting the non-round shape of the leading end of the tubing. In this position, the tubing is completely formed and the mandrel 38 may thereafter be retracted by the ram 42, the die portions 12 and 14 and the rollers 28 and 30 split apart, and the ram 58 retracted so that the bent tubing may be removed from the die.

From the foregoing, it is apparent that the present i11- ventlon represents an improvement over the previous practice of using incompressible filler material within the tubing in order to prevent it from collapsing during bending by eliminating the nal undesirable step of heating the tubing after it is bent to me'lt the incompressible filler material while still enabling the tubing to be bent with the same Iradius of curvature thatcan be obtained when the incompressible filler material is employed.

The present inventionsalso provides a distinct improvement over the previously described prior art methods of bending tubing by inserting a solid mandrel therein in that the tubing can be bent far more sharply and with a much smalier radius of curvature. By way of example, when tubing is bent with a sectional mandrel inserted therein as previously described the minimum recommended bend radius that can be obtained in accordance with standard practice is equal to the `diameter of the tubing being bent. When the tubing is bent with a sheep nose mandrel inserted therein, the minimum recommended bend radius is equal to one and one half times the diameter of the tubing being bent. In direct contrast with this, the minimum bend radius that can be obtained by the present invention which does not insert anything within the tubing for the purposes of bend-ing it is equal to one half the diameter of lthe tubing being bent.

While it will be apparent that the preferred embodiment of the invention herein disclosed is well ca-'lculated to fulil the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

l. Apparatus for bending tubing comprising a split die having a cylindrical passageway therethrough, said passageway having agcurved portion intermediate the ends thereof, and split rolier means rotatably mounted on said die adjacent the convex side o-f said curved portion, a portion of the periphery of said roller forming a portion of the wall of said curved portion of the passageway.

2. The subject matter as claimed in claim l including mandrel means having one end thereof adapted to be insented within one end of said passageway for reforming the leading end of a piece of tubing yafter it has been pushed into said passageway lfrom the other end thereof and around said curved portion.

3. Apparatus for bending tubing comprising a'split die having a cylindrical passageway therethrough, said passageway having a curved portion intermediate the ends thereof, and split rol'ler meansrotatably mountedon said die adjacent the convex side of said curved portion, the axis of said roller means being perpendicular to the plane defined by the curved axis of said passageway, said roller means having a periphery of concave arcuate cross section with substantially the same radius of curvature as said cylindrical passageway, a portion of the periphery of said roller means'fforming a portion of the Wall on the convex side of said curved portion of the passageway.

4. The subject matter as claimed in claim 3 including mandrel means having one end thereof `adapted to be inserted within one end of said pasageway for reforming the leading end of a piece of tubing after it has been pushed into said pasageway from the -other end thereof and around said curved portion, and reciprocating means for reciprocating said mandrel means between a position wherein one end of the mandrel means extends within said one end of the passageway a suicient distance to engage the leading end of lthe piece of tubing after it has been Vformed in said split die Iand a retracted position wherein said one end of the mandrel is retracted a suicient distance to clear the leading end of the tubing.

5. The subject matter as claimed in claim 3 including means for rotatably driving said roller means.

6. Apparatus -for bending tubing comprising a split die having Va cylindricai passageway therethrough, said passageway having la curved portion intermediate the ends thereof, and split roller means rotatably mounted in said die adjacent'the convex side of said curved portion, the axis of said roller means being perpendicular to the plane defined by the curved axis of said passageway, said roller means having la periphery of concave arcuate cross section with the same radius of curvature as said cylindrical passageway and forming a portion of the convex side of the Wall of said curved portion of the passageway, ram means for pushing a piece of tubing into one end of said passageway around said arcuate portion thereof and over said roller means, rack means actuatedV by said ram means for rotatably driving said roller means as said ram means pushes said tubing through said passageway, mandrel mean-s having one end thereof adapted to be lreciprocated within the other end of said passageway and to be inserted within the leading end of the piece of tubing after it has passed around said curved portion to correct any deformation of the leading end resulting from the bending of the tubing, and ram means for reciprocating said mandrel means within said other end of the passageway from a position wherein said one end of said mandrel means can be disposed Within the leading end of the rtubing after it has been bent and a retracted position wherein said one end of said mandrel means clears the leading end of the References Cited in the file of Ithis patent UNITED STATES PATENTS Williams May 1,

Wurzburger Aug. 16,

Wurzburger Apr. 22,

Hitz Oct. 21,

FOREIGN PATENTS Germany Mar. 26, 

